package net;

import java.io.IOException;
import java.net.DatagramPacket;
import java.net.DatagramSocket;
import java.net.SocketException;

public class UdpEchoServer {
    DatagramSocket socket=null;
    public UdpEchoServer(int port) throws SocketException {
        socket=new DatagramSocket(port);
    }

    public void start() throws IOException {
        while (true){
            DatagramPacket requestPacket=new DatagramPacket(new byte[4096],4096);
            socket.receive(requestPacket);
            String request=new String(requestPacket.getData(),0, requestPacket.getLength());
            String response=process(request);
            DatagramPacket responsePacket=new DatagramPacket(response.getBytes(),response.getBytes().length,requestPacket.getSocketAddress());
            socket.send(responsePacket);
            System.out.printf("[%s:%d] req: %s; resp: %s\n",requestPacket.getAddress().toString(),requestPacket.getPort(),request,response);
        }
    }
    public String process(String request){
        return request;
    }

    public static void main(String[] args) throws IOException {
        UdpEchoServer server=new UdpEchoServer(9090);
        server.start();
    }





















//    private DatagramSocket socket=null;
//    public UdpEchoServer(int port) throws SocketException {
//        socket=new DatagramSocket(port);
//    }
//    public void start() throws IOException {
//        System.out.println("服务器启动");
//        while (true){
//            DatagramPacket requestPaket=new DatagramPacket(new byte[4096],4096);
//            socket.receive(requestPaket);
//
//            String request=new String(requestPaket.getData(),0,requestPaket.getLength());
//
//            String response=process(request);
//
//            DatagramPacket responsePacket=new DatagramPacket(response.getBytes(),response.getBytes().length,requestPaket.getSocketAddress());
//        }
//    }
//
//    private String process(String request){
//        return request;
//    }
}
